What is Cat's Claw?

Cat's Claw (Uncaria tomentosa) is a large climbing vine indigenous to the Amazon basin and other tropical areas of Central and South America. The bark and root have been used in traditional medicine by indigenous Amazonian peoples for at least 2,000 years to treat inflammation, infections, and gastrointestinal disorders. Today it is sold globally as a dietary supplement, most commonly standardized to its pentacyclic oxindole alkaloid (POA) content.

How does Cat's Claw work?

Cat's Claw exerts its effects primarily through inhibition of the pro-inflammatory transcription factor NF-κB, reducing downstream production of TNF-alpha, interleukin-1β, and other inflammatory cytokines. Its pentacyclic oxindole alkaloids (POAs) appear to stimulate immune cell activity, including enhancement of phagocytosis and T-lymphocyte function. The quinovic acid glycosides also contribute antioxidant activity, helping to neutralize reactive oxygen species involved in tissue damage.

What forms does Cat's Claw come in?

Standardized extracts (capsules or tablets) provide the most consistent POA content and are the form used in most clinical studies, typically standardized to 1.3–3% POA content. Bark decoctions and teas are the traditional preparation but offer variable alkaloid concentrations. Tinctures provide intermediate bioavailability. Products explicitly labeled as TOA-free are often marketed for superior immunological effect, though direct comparative human trial data on this claim remain limited.

Where it comes from:

Indigenous Amazonian communities, including the Asháninka of Peru, have used Cat's Claw bark preparations for at least two millennia to treat arthritis, stomach disorders, and infections. It was introduced to European herbal medicine in the 1970s through the work of Austrian researcher Klaus Keplinger, who patented extraction methods and brought global scientific attention to its alkaloid constituents.

What does Cat's Claw help with?

• Rheumatoid Arthritis: Cat's Claw inhibits NF-κB-mediated transcription of TNF-alpha and IL-1β, cytokines central to the synovial inflammation and joint destruction characteristic of rheumatoid arthritis. A double-blind, placebo-controlled pilot RCT by Mur et al. (2002) in Rheumatology International (n=40) found that Uncaria tomentosa extract (60 mg/day of a standardized POA extract) added to conventional treatment with sulfasalazine or hydroxychloroquine significantly reduced the number of painful and swollen joints versus placebo after 24 weeks, with no significant adverse events. Evidence is promising but the trial was small and replication in larger RCTs is needed before strong conclusions are drawn.
• Osteoarthritis: Cat's Claw reduces joint inflammation through NF-κB inhibition and antioxidant activity, which may attenuate cartilage degradation and pain signaling in osteoarthritis. A randomized, double-blind, placebo-controlled trial by Piscoya et al. (2001) published in Inflammation Research (n=45) found that a freeze-dried aqueous extract of Uncaria guianensis (100 mg/day) significantly reduced pain with activity, medical assessment scores, and patient global assessment scores after 4 weeks compared to placebo, with rapid onset within the first week. Effects on pain at rest and knee circumference did not reach statistical significance, indicating moderate rather than comprehensive benefit.
• Immune Support: The pentacyclic oxindole alkaloids in Cat's Claw appear to stimulate phagocytosis and proliferation of lymphocytes, suggesting an immunostimulant effect. An open-label pilot study by Lamm et al. (2001) in Phytomedicine (n=27) found that supplementation with a TOA-free Cat's Claw extract alongside a pneumococcal vaccine enhanced IgG antibody response compared to vaccine alone, suggesting adjuvant immune activity. This is preliminary evidence from a non-blinded study and should not be interpreted as established clinical efficacy for immune enhancement broadly.
• Inflammation: Beyond specific diseases, Cat's Claw's NF-κB inhibitory and antioxidant mechanisms provide a general anti-inflammatory profile that may benefit conditions driven by chronic low-grade inflammation. In vitro studies confirm robust NF-κB inhibition and TNF-alpha suppression at clinically relevant concentrations. Human trial data specifically targeting systemic inflammatory markers (e.g., CRP, ESR) as a primary outcome are limited, but improvements in these markers have been observed as secondary endpoints in the arthritis trials cited above.

What can Cat's Claw help prevent?

• Reduction of joint damage progression in early rheumatoid arthritis (preliminary evidence from Mur et al. 2002; not confirmed in long-term trials)

What are the side effects of Cat's Claw?

• Nausea (most commonly reported, particularly on empty stomach)
• Diarrhea or loose stools
• Abdominal cramping
• Dizziness (rare, possibly related to hypotensive alkaloid activity)
• Headache (rare)
• Potential hypotension at high doses
• Theoretical increased bleeding risk with antiplatelet constituents
• Rare reports of kidney damage at very high doses (case reports, not confirmed in controlled trials)

Good to know:

Cat's Claw is generally considered safe at recommended doses in short-to-medium term use (up to 24 weeks in clinical trials), with most adverse events being mild and gastrointestinal in nature. High-dose or long-term safety data in humans are lacking. Contraindicated in pregnancy, breastfeeding, and prior to surgery due to antiplatelet effects.

How much Cat's Claw should you take?

• Recommended daily: Standardized extract (standardized to POA content): 250–350 mg once or twice daily (500–700 mg/day total). Traditional bark decoction: 1–2 g of dried bark boiled in water for 15 minutes, 2–3 times daily. Rheumatoid arthritis trials used 60 mg/day of a specific POA-standardized extract; osteoarthritis trial used 100 mg/day of freeze-dried extract — dose should match the preparation's standardization.
• Best time of day: With meals to minimize GI side effects; no evidence favoring morning versus evening specifically
• With or without food: Take with food — reduces risk of nausea and GI discomfort, and may improve tolerability in sensitive individuals
• Time to effect: 4–8 weeks for joint pain and inflammation; some immune-related changes reported within 2–4 weeks
• How long to take it: Most clinical trials ran 4–24 weeks. For chronic conditions, use for 8–12 weeks then reassess with a healthcare provider. Cycling (e.g., 8 weeks on, 2–4 weeks off) is commonly recommended in traditional herbalism but lacks formal clinical evidence. Not recommended for continuous use beyond 6 months without medical supervision due to absence of long-term safety data.